The Ho Chi Minh City Traffic Police said Sunday it has seized and held on to 21 motorbikes since it began the campaign on August 16.

Some of the violators did not admit their mistakes and refused to sign documents, it said.

Among them was an American who drove a motorbike without a helmet on Bui Vien Street in District 1 on August 16. When the police pulled him over, he did not present papers and became confrontational.

After officers explained his mistakes in English, the man left his motorbike and walked away. 

Police said that difference in languages was a main problem in working with foreign violators. A session typically takes 60-80 minutes, much longer than with a Vietnamese.

Lawyer Do Ngoc Thanh said that both Vietnamese and foreigners should be fined equally when they violate the laws, but there should be a clearer mechanism for foreigners to understand their mistakes.

He said there should be interpreters who are not from the police to facilitate the conversation to ensure fairness, and all documents should be written in both Vietnamese and English.

Ho Chi Minh City received more than 4.2 million foreign tourists in the first half of this year, a 10 percent jump year-on-year. It expects 8.5 million to visit this year.

Police say the city has the highest number of foreign traffic violators in the country. Popular violations are riding without a license, with no helmets, disobeying traffic lights and signs and riding on the wrong lane.

Data from the Ministry of Labor, Invalids, and Social Affairs shows the number of foreign employees in Vietnam increased from 63,557 in 2011 to 83,046 in 2016.